Preheat the oven to 350˚F. Generously coat a 9 by 5-inch loaf pan with nonstick cooking spray.
Using the largest holes on a box grater, grate the zucchini. Wrap in a clean tea towel and place in a colander. Use your hands to squeeze out as much excess as possible, then set aside.
In a medium bowl, whisk together flour, cinnamon, baking soda, baking powder, salt and nutmeg. Set aside.
In a large bowl, whisk together brown sugar, olive oil, Greek yogurt, eggs and vanilla extract. Fold the dry ingredient in with a rubber spatula. When only a few streaks of flour remain, add drained zucchini and walnuts and fold until combined.
Scrape the batter into the prepared pan and bake for 70 to 75 minutes, or until a cake tester inserted in the center of the cake comes out clean.
Remove from oven and let cool completely on a wire rack before removing from loaf pan.
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Notes
Storage: Zucchini bread can be stored in an airtight container or tightly wrapped in plastic wrap and kept at room temperature for up to 3 days. After that, transfer to the fridge for up to 1 week.To freeze, tightly wrap individual slices or the whole loaf and place in freezer safe bag. Freeze for up to 3 months. Thaw overnight at room temperature.Tips:Don't worry about peeling the zucchini. There's no need with this recipe because you'll barely notice them and it blends in with the inner parts of the zucchini. Plus it adds more fiber to the recipe this way!Remove as much excess moisture from the zucchini as possible. Failing to drain it properly will result in a gummy consistency of the final bread.Note the longer bake time up to 75 minutes. This loaf takes quite a while to bake through thanks to all the moisture the zucchini adds. If you find the top is browning too much before the middle is cooked, you can loosely tent the top of the bread with foil.Use a thermometer to check for doneness. The toothpick or knife trick will work well but because this loaf is so large, it will appear done on top and may be crumb free but still need a few more minutes of cooking at the bottom. Quick bread doneness temperature should be at 200°F.